Often when America suffers some large, inexplicable tragedy, we want to blame "foreigners" and look for ways to fortify ourselves against them. It's more reassuring to believe that an evil lies outside our borders -- in "them" -- than to face the possibility that it's randomly among us.

And like the communist scare before it, the so-called "war on terror" -- a war without end -- offers a convenient means of targeting the source as a foreign menace bent on destroying us.

Let's blame immigrants, say the xenophobes. Sen. Rand Paul, Republican of Kentucky, is urging Senate Majority Leader Harry Reid, a Nevada Democrat, to reconsider immigration reform because of the bombings. "The facts emerging in the Boston Marathon bombing have exposed a weakness in our current system," Mr. Paul says.

Sen. Chuck Grassley of Iowa, the senior Republican on the Senate Judiciary Committee, which is responsible for an immigration reform bill, is using much the same language -- suggesting that the investigation of the two alleged Boston attackers will "help shed light on the weaknesses of our system."

Whatever "weaknesses" exist in our immigration system don't explain why Dzhokhar Tsarnaev did what he is alleged to have done. He came to the United States when he was 9 years old and attended the public schools of Cambridge, Mass., not far from where I lived.

Immigration reform shouldn't be confused with national security in any event. The main purpose of reforming our outmoded immigration laws is to do what's right and give the estimated 11 million undocumented immigrants in America -- many of them here for years, working at jobs and paying withholding taxes, and many of them children -- a path to citizenship.

We need to make sure they aren't exploited by employers and others who know they won't complain to authorities. And we should give their families the possibility of living here peacefully and securely without fearing deportation.

That path shouldn't be so easy as to invite others from abroad to abuse the system. America has every right to demand that undocumented immigrants pay a penalty and move to the back of the queue when it comes to attaining citizenship.

But the path should be reasonable, straightforward and fair.

The new xenophobia doesn't end there. Other politicians want to declare the surviving Boston bombing suspect an "enemy combatant" and deny him the protections of the criminal justice system.

Sen. Lindsey Graham, Republican of South Carolina, argues this is necessary given "his radical Islamist ties and the fact that Chechens are all over the world fighting with al-Qaida."

Wait a moment. Mr. Tsarnaev was arrested on American soil for acts occurring in the United States. No known evidence links him to al-Qaida. He is Muslim, but does Mr. Graham believe Muslims are presumed guilty until proven otherwise?

It's true that during the Bush administration the Supreme Court upheld the indefinite military detention of Yaser Esam Hamdi, who was an American citizen. But the Hamdi case was entirely different. Mr. Hamdi was captured carrying a weapon on an Afghanistan battlefield. The court said the purpose of wartime detention was to keep captured enemies from returning to fight, and that "indefinite detention for the purpose of interrogation is not authorized."

The so-called "war on terror" is analogous to the Cold War, which lasted almost 45 years. During its height we came perilously close to abrogating the rights of American citizens on suspicions they had ties to communists.

If American citizens can be arrested and held indefinitely without a lawyer or proper trial, and without the full protection of our system of justice, because we suspect they have ties to terrorists, where will that end?

Our civil rights and liberties lie at the core of what it means to be an American. We have fought for over two centuries to protect and defend them.

The horror of the Boston Marathon bombing is legitimate. But the xenophobic fears it has aroused are not.

We need immigration reform. We must protect our civil liberties. These goals are not incompatible with protecting America. They are essential to it.

Robert Reich, former U.S. secretary of labor, is professor of public policy at the University of California at Berkeley and the author of "Beyond Outrage," now available in paperback. He blogs at www.robertreich.org.

As much as I would love to see monster Dzhokhar Tsarnaev executed, one consideration holds me back and is missing from your report. Namely, if he were put to death, it would make him a martyr in the eyes of radical Islamic terrorists ("Death penalty sought for alleged Boston bomber Tsarnaev," Jan....

Dzhokhar Tsarnaev is a monster, but that shouldn't restrict investigation into his beliefs that led up to the Boston Marathon bombing. This act of terrorism was abhorrent, but I don't fault Rolling Stone for doing an article on the subject, or for putting the remaining suspect's photo on the cover...

There are 875,000 on the terrorist watch list ("U.S. launches internal review," May 1). Unbelievable! This speaks out against the effectiveness of our immigration screening system and homeland security apparatus.